THE PERIOSTEAL OSTEOSARCOMA - HISTOLOGICA L CHARACTERISTICS, PREPARATION TECHNIQUE, GROWTH-PATTERN, AND DIFFERENTIAL-DIAGNOSIS

Periosteal osteosarcoma is a distinct bone tumor entity with character istic morphological features within the group of juxtacortical osteosa rcoma. Periosteal osteosarcoma is predominantly located in the long tu bular bones, especially in the tibia and femur and is situated on the outer circumference of the tumor-bearing bone (saucerization phenomeno n). In contrast to parosteal osteosarcoma, periosteal osteosarcoma is less differentiated and is believed to have a worse prognosis. In this work the histological features are described with predominantly chond roblastic differentiation of 14 cases with periosteal osteosarcoma. A horizontal preparation technique of periosteal osteosarcoma specimens allows comparison with computed tomography and is the optimal method t o detect an invasion of the medullary cavity. Further studies are nece ssary to clarify if neoadjuvant chemotherapy could improve the prognos is of certain patients.